/*

 * Copyright (c) 2002, 2012, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 *

 */

#include "precompiled.hpp"

#include "gc_implementation/parallelScavenge/parallelScavengeHeap.hpp"

#include "gc_implementation/parallelScavenge/psOldGen.hpp"

#include "gc_implementation/parallelScavenge/psPromotionManager.inline.hpp"

#include "gc_implementation/parallelScavenge/psScavenge.inline.hpp"

#include "gc_implementation/shared/mutableSpace.hpp"

#include "memory/memRegion.hpp"

#include "oops/oop.inline.hpp"

#include "oops/oop.psgc.inline.hpp"

PSPromotionManager**         PSPromotionManager::_manager_array = NULL;

OopStarTaskQueueSet*         PSPromotionManager::_stack_array_depth = NULL;

PSOldGen*                    PSPromotionManager::_old_gen = NULL;

MutableSpace*                PSPromotionManager::_young_space = NULL;

void PSPromotionManager::initialize() {

  ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();

  assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");

  _old_gen = heap->old_gen();

  _young_space = heap->young_gen()->to_space();

  assert(_manager_array == NULL, "Attempt to initialize twice");

  guarantee(_manager_array != NULL, "Could not initialize promotion manager");

  _stack_array_depth = new OopStarTaskQueueSet(ParallelGCThreads);

  guarantee(_stack_array_depth != NULL, "Cound not initialize promotion manager");

  // Create and register the PSPromotionManager(s) for the worker threads.

  for(uint i=0; i<ParallelGCThreads; i++) {

    _manager_array[i] = new PSPromotionManager();

    guarantee(_manager_array[i] != NULL, "Could not create PSPromotionManager");

    stack_array_depth()->register_queue(i, _manager_array[i]->claimed_stack_depth());

  }

  // The VMThread gets its own PSPromotionManager, which is not available

  // for work stealing.

  _manager_array[ParallelGCThreads] = new PSPromotionManager();

  guarantee(_manager_array[ParallelGCThreads] != NULL, "Could not create PSPromotionManager");

}

PSPromotionManager* PSPromotionManager::gc_thread_promotion_manager(int index) {

  assert(index >= 0 && index < (int)ParallelGCThreads, "index out of range");

  assert(_manager_array != NULL, "Sanity");

  return _manager_array[index];

}

PSPromotionManager* PSPromotionManager::vm_thread_promotion_manager() {

  assert(_manager_array != NULL, "Sanity");

  return _manager_array[ParallelGCThreads];

}

void PSPromotionManager::pre_scavenge() {

  ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();

  assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");

  _young_space = heap->young_gen()->to_space();

  for(uint i=0; i<ParallelGCThreads+1; i++) {

    manager_array(i)->reset();

  }

}

void PSPromotionManager::post_scavenge() {

  TASKQUEUE_STATS_ONLY(if (PrintGCDetails && ParallelGCVerbose) print_stats());

  for (uint i = 0; i < ParallelGCThreads + 1; i++) {

    PSPromotionManager* manager = manager_array(i);

    assert(manager->claimed_stack_depth()->is_empty(), "should be empty");

    manager->flush_labs();

  }

}

#if TASKQUEUE_STATS

void

PSPromotionManager::print_taskqueue_stats(uint i) const {

  tty->print("%3u ", i);

  _claimed_stack_depth.stats.print();

  tty->cr();

}

void

PSPromotionManager::print_local_stats(uint i) const {

  #define FMT " " SIZE_FORMAT_W(10)

  tty->print_cr("%3u" FMT FMT FMT FMT, i, _masked_pushes, _masked_steals,

                _arrays_chunked, _array_chunks_processed);

  #undef FMT

}

static const char* const pm_stats_hdr[] = {

  "    --------masked-------     arrays      array",

  "thr       push      steal    chunked     chunks",

  "--- ---------- ---------- ---------- ----------"

};

void

PSPromotionManager::print_stats() {

  tty->print_cr("== GC Tasks Stats, GC %3d",

                Universe::heap()->total_collections());

  tty->print("thr "); TaskQueueStats::print_header(1); tty->cr();

  tty->print("--- "); TaskQueueStats::print_header(2); tty->cr();

  for (uint i = 0; i < ParallelGCThreads + 1; ++i) {

    manager_array(i)->print_taskqueue_stats(i);

  }

  const uint hlines = sizeof(pm_stats_hdr) / sizeof(pm_stats_hdr[0]);

  for (uint i = 0; i < hlines; ++i) tty->print_cr(pm_stats_hdr[i]);

  for (uint i = 0; i < ParallelGCThreads + 1; ++i) {

    manager_array(i)->print_local_stats(i);

  }

}

void

PSPromotionManager::reset_stats() {

  claimed_stack_depth()->stats.reset();

  _masked_pushes = _masked_steals = 0;

  _arrays_chunked = _array_chunks_processed = 0;

}

#endif // TASKQUEUE_STATS

PSPromotionManager::PSPromotionManager() {

  ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();

  assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");

  // We set the old lab's start array.

  _old_lab.set_start_array(old_gen()->start_array());

  uint queue_size;

  claimed_stack_depth()->initialize();

  queue_size = claimed_stack_depth()->max_elems();

  _totally_drain = (ParallelGCThreads == 1) || (GCDrainStackTargetSize == 0);

  if (_totally_drain) {

    _target_stack_size = 0;

  } else {

    // don't let the target stack size to be more than 1/4 of the entries

    _target_stack_size = (uint) MIN2((uint) GCDrainStackTargetSize,

                                     (uint) (queue_size / 4));

  }

  _array_chunk_size = ParGCArrayScanChunk;

  // let's choose 1.5x the chunk size

  _min_array_size_for_chunking = 3 * _array_chunk_size / 2;

  reset();

}

void PSPromotionManager::reset() {

  assert(stacks_empty(), "reset of non-empty stack");

  // We need to get an assert in here to make sure the labs are always flushed.

  ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();

  assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");

  // Do not prefill the LAB's, save heap wastage!

  HeapWord* lab_base = young_space()->top();

  _young_lab.initialize(MemRegion(lab_base, (size_t)0));

  _young_gen_is_full = false;

  lab_base = old_gen()->object_space()->top();

  _old_lab.initialize(MemRegion(lab_base, (size_t)0));

  _old_gen_is_full = false;

  TASKQUEUE_STATS_ONLY(reset_stats());

}

void PSPromotionManager::drain_stacks_depth(bool totally_drain) {

  totally_drain = totally_drain || _totally_drain;

#ifdef ASSERT

  ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();

  assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");

  MutableSpace* to_space = heap->young_gen()->to_space();

  MutableSpace* old_space = heap->old_gen()->object_space();

  MutableSpace* perm_space = heap->perm_gen()->object_space();

#endif /* ASSERT */

  OopStarTaskQueue* const tq = claimed_stack_depth();

  do {

    StarTask p;

    // Drain overflow stack first, so other threads can steal from

    // claimed stack while we work.

    while (tq->pop_overflow(p)) {

      process_popped_location_depth(p);

    }

    if (totally_drain) {

      while (tq->pop_local(p)) {

        process_popped_location_depth(p);

      }

    } else {

      while (tq->size() > _target_stack_size && tq->pop_local(p)) {

        process_popped_location_depth(p);

      }

    }

  } while (totally_drain && !tq->taskqueue_empty() || !tq->overflow_empty());

  assert(!totally_drain || tq->taskqueue_empty(), "Sanity");

  assert(totally_drain || tq->size() <= _target_stack_size, "Sanity");

  assert(tq->overflow_empty(), "Sanity");

}

void PSPromotionManager::flush_labs() {

  assert(stacks_empty(), "Attempt to flush lab with live stack");

  // If either promotion lab fills up, we can flush the

  // lab but not refill it, so check first.

  assert(!_young_lab.is_flushed() || _young_gen_is_full, "Sanity");

  if (!_young_lab.is_flushed())

    _young_lab.flush();

  assert(!_old_lab.is_flushed() || _old_gen_is_full, "Sanity");

  if (!_old_lab.is_flushed())

    _old_lab.flush();

  // Let PSScavenge know if we overflowed

  if (_young_gen_is_full) {

    PSScavenge::set_survivor_overflow(true);

  }

}

template <class T> void PSPromotionManager::process_array_chunk_work(

                                                 oop obj,

                                                 int start, int end) {

  assert(start <= end, "invariant");

  T* const base      = (T*)objArrayOop(obj)->base();

  T* p               = base + start;

  T* const chunk_end = base + end;

  while (p < chunk_end) {

    if (PSScavenge::should_scavenge(p)) {

      claim_or_forward_depth(p);

    }

    ++p;

  }

}

void PSPromotionManager::process_array_chunk(oop old) {

  assert(PSChunkLargeArrays, "invariant");

  assert(old->is_objArray(), "invariant");

  assert(old->is_forwarded(), "invariant");

  TASKQUEUE_STATS_ONLY(++_array_chunks_processed);

  oop const obj = old->forwardee();

  int start;

  int const end = arrayOop(old)->length();

  if (end > (int) _min_array_size_for_chunking) {

    // we'll chunk more

    start = end - _array_chunk_size;

    assert(start > 0, "invariant");

    arrayOop(old)->set_length(start);

    push_depth(mask_chunked_array_oop(old));

    TASKQUEUE_STATS_ONLY(++_masked_pushes);

  } else {

    // this is the final chunk for this array

    start = 0;

    int const actual_length = arrayOop(obj)->length();

    arrayOop(old)->set_length(actual_length);

  }

  if (UseCompressedOops) {

    process_array_chunk_work<narrowOop>(obj, start, end);

  } else {

    process_array_chunk_work<oop>(obj, start, end);

  }

}

oop PSPromotionManager::oop_promotion_failed(oop obj, markOop obj_mark) {

  assert(_old_gen_is_full || PromotionFailureALot, "Sanity");

  // Attempt to CAS in the header.

  // This tests if the header is still the same as when

  // this started.  If it is the same (i.e., no forwarding

  // pointer has been installed), then this thread owns

  // it.

  if (obj->cas_forward_to(obj, obj_mark)) {

    // We won any races, we "own" this object.

    assert(obj == obj->forwardee(), "Sanity");

    obj->push_contents(this);

    // Save the mark if needed

    PSScavenge::oop_promotion_failed(obj, obj_mark);

  }  else {

    // We lost, someone else "owns" this object

    guarantee(obj->is_forwarded(), "Object must be forwarded if the cas failed.");

    // No unallocation to worry about.

    obj = obj->forwardee();

  }

#ifdef DEBUG

  if (TraceScavenge) {

    gclog_or_tty->print_cr("{%s %s 0x%x (%d)}",

                           "promotion-failure",

                           obj->blueprint()->internal_name(),

                           obj, obj->size());

  }

#endif

  return obj;

}